Gliederung

The spike protein (S) of severe acute respiratory syndrome associated coronavirus (SARS-CoV), a close relative to coronavirus group 2, is a type I glycoprotein, which forms large spikes on the surface of the virion. The ectodomain of the spike protein is extensively N-glycosylated and is essential for the interaction with host cell receptors and membrane fusion. The protein consists of 1255 amino acids containing 17 potential N-glycosylation sites, a signal peptide and a C-terminal membrane anchor. Some coronavirus spike proteins (MHV, HCoV-OC43, AIBV and BCoV), but not all (TGV, FIPV, HCoV-229E) are proteolytically cleaved in two subunits, S1 and S2, carboxyterminal of a basic amino acid motive recognized by subtilase furin. Whether cleavage is essential for the function of S proteins of all coronaviruses is still under discussion.